There has been and continues to be a need to provide an individual with improved visual acuity or visual benefit. One of known solutions is to use contact lenses in correcting adverse vision conditions. Current contact lenses have a relatively simple surface design and generally are rotationally-symmetric or toric. These contact lenses are able to correct low-order aberrations of the human eye, such as defocus, astigmatism and prism. For people who only have these low-order monochromatic aberrations of the eyes, their visual acuity can be improved to 20/20 or better by wearing current contact lenses. However, current contact lenses are unable to correct high-order monochromatic aberrations of the human eye, such as a non-standard amount of spherical aberration, coma, and other irregular high-order aberrations. These high order aberrations blur images formed on the retina, which can impair vision. The impact of these higher-order aberrations on retinal image quality can become significant in some cases, for example, in older eyes, in normal eyes with large pupils, and in the eyes of many people with irregular astigmatism, keratoconus, corneal dystrophies, post penetrating keratoplasty, scarring from ulcerative keratitis, corneal trauma with and without surgical repair, and sub-optimal outcome following refractive surgery. For those people, visual acuity of 20/20 or better can be achieved with customized contact lenses or contact lenses capable of correcting high-order monochromatic aberrations of the human eye.
Unlike current contact lenses, customized contact lenses or contact lenses capable of correcting high order aberrations inevitably need to have a complex surface design and/or a spatial distribution of index of refraction. The design, production and metrology-characterization of such contact lenses with complex surfaces and spatial distribution of index of refraction can not be met by current lens designing, manufacturing and characterizing technologies.
U.S. Pat. No. 6,241,355 discloses a method of computer-aided contact lens design using spline-based mathematical surfaces without restrictions of rotational symmetry. The patent teaches that each of the anterior surface, posterior surface and peripheral edge system of a contact lens can be described by one or a plurality of piecewise functions that satisfy a set of associated constraints of smoothness and thereby a contact lens can be produced to have a posterior surface that provides a good fit to a cornea having a complicated shape. However, the patent does not disclose how to design and fabricate a contact lens capable of correcting high-order aberrations, nor suggest that the design and fabrication of a contact lens capable of correcting high-order aberrations can be accomplished.
U.S. Pat. Nos. 5,777,719 and 6,095,651 disclose a concept that contact lenses for correcting at least third-order wavefront aberrations of the living eye might be fabricated based on a final correction signal that control a deformable mirror to compensate for the aberrations of the living eye. Although the patents teach that high-order aberrations of the human eye can be measured by using a Hartmann-Shack wavefront sensor and then corrected in a closed feedback loop with a deformable mirror as a compensating optical-component, there are no methods or algorithms defined for converting the final correction signal, that controls a reflective optics (i.e., a deformable mirror) to compensate for the aberrations, into a signal, that produces a refractive optics (i.e., a contact lens) capable of correcting the aberrations, nor examples which shows that a contact lens can be fabricated to correct high-order aberrations.
U.S. Pat. No. 6,086,204 discloses a method for correcting the optical aberrations beyond defocus and astigmatism of an eye fitted with an original contact lens having a known anterior surface shape by providing a modified or new contact lens which has its anterior surface reshaped from said original contact lens's anterior surface. The patent teaches that a modified or new contact lens is produced by first measuring the optical aberrations of an eye fitted with an original contact lens, then performing a mathematical analysis of the eye's optical aberrations when fitted with the original contact lens to determine the modified anterior surface shape, and finally fabricating the modified anterior surface by methods that remove, add or compress material or alter the surface chemistry. There are some limitations in the method disclosed in U.S. Pat. No. 6,086,204. First, the posterior surface is not variable and is predetermined by the original contact lens. Second, a first contact lens, that is unable to correct high-order aberrations, must be fabricated, then be tried on by a patient, and finally be modified or a new contact lens having a posterior surface identical to that of the original contact lens is fabricated. The method disclosed in U.S. Pat. No. 6,086,204 could have a long lens design cycle and concept evaluation time.
WO-A-01/11418 discloses a system and method of integrating corneal topographic data and ocular wavefront data with primary ametropia measurements to create a soft contact lens design. WO-A-01/11418 teaches that a better fitting soft contact lens can be designed by achieving a contact lens back surface which is uniquely matched to a particular corneal topography, or which is an averaged shape based on the particular corneal topography.
However, WO-A-01/11418 does not disclose nor suggest how to design and fabricate a contact lens capable of correcting high-order aberrations.
There still remains a need for a system and method for designing and/or fabricating contact lenses capable of correcting high-order aberrations of an eye. There is also a need for a system and method for characterizing the metrology of a contact lens capable of correcting high-order aberrations of an eye.